lib/spinlock_debug.c

   1 /*
   2  * Copyright 2005, Red Hat, Inc., Ingo Molnar
   3  * Released under the General Public License (GPL).
   4  *
   5  * This file contains the spinlock/rwlock implementations for
   6  * DEBUG_SPINLOCK.
   7  */
   8
   9 #include <linux/spinlock.h>
  10 #include <linux/nmi.h>
  11 #include <linux/interrupt.h>
  12 #include <linux/debug_locks.h>
  13 #include <linux/delay.h>
  14 #include <linux/export.h>
  15
  16 void __raw_spin_lock_init(raw_spinlock_t *lock, const char *name,
  17                           struct lock_class_key *key)
  18 {
  19 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  20         /*
  21          * Make sure we are not reinitializing a held lock:
  22          */
  23         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  24         lockdep_init_map(&lock->dep_map, name, key, 0);
  25 #endif
  26         lock->raw_lock = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED;
  27         lock->magic = SPINLOCK_MAGIC;
  28         lock->owner = SPINLOCK_OWNER_INIT;
  29         lock->owner_cpu = -1;
  30 }
  31
  32 EXPORT_SYMBOL(__raw_spin_lock_init);
  33
  34 void __rwlock_init(rwlock_t *lock, const char *name,
  35                    struct lock_class_key *key)
  36 {
  37 #ifdef CONFIG_DEBUG_LOCK_ALLOC
  38         /*
  39          * Make sure we are not reinitializing a held lock:
  40          */
  41         debug_check_no_locks_freed((void *)lock, sizeof(*lock));
  42         lockdep_init_map(&lock->dep_map, name, key, 0);
  43 #endif
  44         lock->raw_lock = (arch_rwlock_t) __ARCH_RW_LOCK_UNLOCKED;
  45         lock->magic = RWLOCK_MAGIC;
  46         lock->owner = SPINLOCK_OWNER_INIT;
  47         lock->owner_cpu = -1;
  48 }
  49
  50 EXPORT_SYMBOL(__rwlock_init);
  51
  52 static void spin_dump(raw_spinlock_t *lock, const char *msg)
  53 {
  54         struct task_struct *owner = NULL;
  55
  56         if (lock->owner && lock->owner != SPINLOCK_OWNER_INIT)
  57                 owner = lock->owner;
  58         printk(KERN_EMERG "BUG: spinlock %s on CPU#%d, %s/%d\n",
  59                 msg, raw_smp_processor_id(),
  60                 current->comm, task_pid_nr(current));
  61         printk(KERN_EMERG " lock: %pS, .magic: %08x, .owner: %s/%d, "
  62                         ".owner_cpu: %d\n",
  63                 lock, lock->magic,
  64                 owner ? owner->comm : "<none>",
  65                 owner ? task_pid_nr(owner) : -1,
  66                 lock->owner_cpu);
  67         dump_stack();
  68 }
  69
  70 static void spin_bug(raw_spinlock_t *lock, const char *msg)
  71 {
  72         if (!debug_locks_off())
  73                 return;
  74
  75         spin_dump(lock, msg);
  76 }
  77
  78 #define SPIN_BUG_ON(cond, lock, msg) if (unlikely(cond)) spin_bug(lock, msg)
  79
  80 static inline void
  81 debug_spin_lock_before(raw_spinlock_t *lock)
  82 {
  83         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  84         SPIN_BUG_ON(lock->owner == current, lock, "recursion");
  85         SPIN_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
  86                                                         lock, "cpu recursion");
  87 }
  88
  89 static inline void debug_spin_lock_after(raw_spinlock_t *lock)
  90 {
  91         lock->owner_cpu = raw_smp_processor_id();
  92         lock->owner = current;
  93 }
  94
  95 static inline void debug_spin_unlock(raw_spinlock_t *lock)
  96 {
  97         SPIN_BUG_ON(lock->magic != SPINLOCK_MAGIC, lock, "bad magic");
  98         SPIN_BUG_ON(!raw_spin_is_locked(lock), lock, "already unlocked");
  99         SPIN_BUG_ON(lock->owner != current, lock, "wrong owner");
 100         SPIN_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 101                                                         lock, "wrong CPU");
 102         lock->owner = SPINLOCK_OWNER_INIT;
 103         lock->owner_cpu = -1;
 104 }
 105
 106 static void __spin_lock_debug(raw_spinlock_t *lock)
 107 {
 108         u64 i;
 109         u64 loops = loops_per_jiffy * HZ;
 110
 111         for (i = 0; i < loops; i++) {
 112                 if (arch_spin_trylock(&lock->raw_lock))
 113                         return;
 114                 __delay(1);
 115         }
 116         /* lockup suspected: */
 117         spin_dump(lock, "lockup suspected");
 118 #ifdef CONFIG_SMP
 119         trigger_all_cpu_backtrace();
 120 #endif
 121
 122         /*
 123          * The trylock above was causing a livelock.  Give the lower level arch
 124          * specific lock code a chance to acquire the lock. We have already
 125          * printed a warning/backtrace at this point. The non-debug arch
 126          * specific code might actually succeed in acquiring the lock.  If it is
 127          * not successful, the end-result is the same - there is no forward
 128          * progress.
 129          */
 130         arch_spin_lock(&lock->raw_lock);
 131 }
 132
 133 void do_raw_spin_lock(raw_spinlock_t *lock)
 134 {
 135         debug_spin_lock_before(lock);
 136         if (unlikely(!arch_spin_trylock(&lock->raw_lock)))
 137                 __spin_lock_debug(lock);
 138         debug_spin_lock_after(lock);
 139 }
 140
 141 int do_raw_spin_trylock(raw_spinlock_t *lock)
 142 {
 143         int ret = arch_spin_trylock(&lock->raw_lock);
 144
 145         if (ret)
 146                 debug_spin_lock_after(lock);
 147 #ifndef CONFIG_SMP
 148         /*
 149          * Must not happen on UP:
 150          */
 151         SPIN_BUG_ON(!ret, lock, "trylock failure on UP");
 152 #endif
 153         return ret;
 154 }
 155
 156 void do_raw_spin_unlock(raw_spinlock_t *lock)
 157 {
 158         debug_spin_unlock(lock);
 159         arch_spin_unlock(&lock->raw_lock);
 160 }
 161
 162 static void rwlock_bug(rwlock_t *lock, const char *msg)
 163 {
 164         if (!debug_locks_off())
 165                 return;
 166
 167         printk(KERN_EMERG "BUG: rwlock %s on CPU#%d, %s/%d, %p\n",
 168                 msg, raw_smp_processor_id(), current->comm,
 169                 task_pid_nr(current), lock);
 170         dump_stack();
 171 }
 172
 173 #define RWLOCK_BUG_ON(cond, lock, msg) if (unlikely(cond)) rwlock_bug(lock, msg)
 174
 175 #if 0           /* __write_lock_debug() can lock up - maybe this can too? */
 176 static void __read_lock_debug(rwlock_t *lock)
 177 {
 178         u64 i;
 179         u64 loops = loops_per_jiffy * HZ;
 180         int print_once = 1;
 181
 182         for (;;) {
 183                 for (i = 0; i < loops; i++) {
 184                         if (arch_read_trylock(&lock->raw_lock))
 185                                 return;
 186                         __delay(1);
 187                 }
 188                 /* lockup suspected: */
 189                 if (print_once) {
 190                         print_once = 0;
 191                         printk(KERN_EMERG "BUG: read-lock lockup on CPU#%d, "
 192                                         "%s/%d, %p\n",
 193                                 raw_smp_processor_id(), current->comm,
 194                                 current->pid, lock);
 195                         dump_stack();
 196                 }
 197         }
 198 }
 199 #endif
 200
 201 void do_raw_read_lock(rwlock_t *lock)
 202 {
 203         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 204         arch_read_lock(&lock->raw_lock);
 205 }
 206
 207 int do_raw_read_trylock(rwlock_t *lock)
 208 {
 209         int ret = arch_read_trylock(&lock->raw_lock);
 210
 211 #ifndef CONFIG_SMP
 212         /*
 213          * Must not happen on UP:
 214          */
 215         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 216 #endif
 217         return ret;
 218 }
 219
 220 void do_raw_read_unlock(rwlock_t *lock)
 221 {
 222         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 223         arch_read_unlock(&lock->raw_lock);
 224 }
 225
 226 static inline void debug_write_lock_before(rwlock_t *lock)
 227 {
 228         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 229         RWLOCK_BUG_ON(lock->owner == current, lock, "recursion");
 230         RWLOCK_BUG_ON(lock->owner_cpu == raw_smp_processor_id(),
 231                                                         lock, "cpu recursion");
 232 }
 233
 234 static inline void debug_write_lock_after(rwlock_t *lock)
 235 {
 236         lock->owner_cpu = raw_smp_processor_id();
 237         lock->owner = current;
 238 }
 239
 240 static inline void debug_write_unlock(rwlock_t *lock)
 241 {
 242         RWLOCK_BUG_ON(lock->magic != RWLOCK_MAGIC, lock, "bad magic");
 243         RWLOCK_BUG_ON(lock->owner != current, lock, "wrong owner");
 244         RWLOCK_BUG_ON(lock->owner_cpu != raw_smp_processor_id(),
 245                                                         lock, "wrong CPU");
 246         lock->owner = SPINLOCK_OWNER_INIT;
 247         lock->owner_cpu = -1;
 248 }
 249
 250 #if 0           /* This can cause lockups */
 251 static void __write_lock_debug(rwlock_t *lock)
 252 {
 253         u64 i;
 254         u64 loops = loops_per_jiffy * HZ;
 255         int print_once = 1;
 256
 257         for (;;) {
 258                 for (i = 0; i < loops; i++) {
 259                         if (arch_write_trylock(&lock->raw_lock))
 260                                 return;
 261                         __delay(1);
 262                 }
 263                 /* lockup suspected: */
 264                 if (print_once) {
 265                         print_once = 0;
 266                         printk(KERN_EMERG "BUG: write-lock lockup on CPU#%d, "
 267                                         "%s/%d, %p\n",
 268                                 raw_smp_processor_id(), current->comm,
 269                                 current->pid, lock);
 270                         dump_stack();
 271                 }
 272         }
 273 }
 274 #endif
 275
 276 void do_raw_write_lock(rwlock_t *lock)
 277 {
 278         debug_write_lock_before(lock);
 279         arch_write_lock(&lock->raw_lock);
 280         debug_write_lock_after(lock);
 281 }
 282
 283 int do_raw_write_trylock(rwlock_t *lock)
 284 {
 285         int ret = arch_write_trylock(&lock->raw_lock);
 286
 287         if (ret)
 288                 debug_write_lock_after(lock);
 289 #ifndef CONFIG_SMP
 290         /*
 291          * Must not happen on UP:
 292          */
 293         RWLOCK_BUG_ON(!ret, lock, "trylock failure on UP");
 294 #endif
 295         return ret;
 296 }
 297
 298 void do_raw_write_unlock(rwlock_t *lock)
 299 {
 300         debug_write_unlock(lock);
 301         arch_write_unlock(&lock->raw_lock);
 302 }